Antibodies, complement proteins, and phagocytic cells provide effective protection against all of the following types of infections in Figure Q2.1, except:

Correct Answer: C

Rationale: Assuming Q2.1 lists infection types, intracellular pathogens (e.g., viruses) resist antibodies/complement/phagocytosis ; extracellular pathogens are cleared.

Correct Answer: D

Rationale: Vertebrate eyes have a single lens where light is focused by the cornea and lens, the lens shape adjusts for near and far vision, and photoreceptors in the retina detect light. All options are correct.

Correct Answer: B

Rationale: Inflammation is a key innate defense mechanism, activating nonspecific responses to injury or infection, unlike active/passive immunity (adaptive) or erythrocyte mobilization.

Correct Answer: B

Rationale: Antigen-antibody complexes activate the complement system, enhancing pathogen destruction, not mediators, membranes, or T cells alone.

Correct Answer: B

Rationale: The alternative pathway is triggered by spontaneous C3 hydrolysis on pathogen surfaces, unlike classical (antibody-driven) or lectin (sugar-binding) pathways.